docs: def save_form(self, request, form, change):
          """Given a ModelForm return an unsaved instance. ``change`` is True if
          the object is being changed, and False if it's being added."""
          instance = super(PageAdmin, self).save_form(request, form, change)
          instance.template = form.cleaned_data['template']
          if not change:
              instance.author = request.user
          return instance